1. Field of the Invention
The present invention relates to an optical rotating recording medium such as a magneto-optical disk and an optical disk, an address information recording method for recording address information on such an optical rotating recording medium, an address information recovery method for reading and recovering address information from such optical rotating recording medium and an optical reproducing apparatus of the same, and an optical recording/reproducing apparatus.
2. Description of the Related Art
FIG. 1 is a schematic view of a magneto-optical disk.
FIG. 2 is an enlarged view of a part of the magneto-optical disk shown in FIG. 1.
A land and a groove are formed adjacent to each other and are formed continuously in a spiral from the center of the magneto-optical disk toward the outer rim. In the case of the illustrated magneto-optical disk of a CAV format, the land LAND and groove GROOVE are respectively provided with headers HEADER at equivalent angles. Inside the respective headers are recorded address information ADDRESS for indicating their positions.
When compared with recording media like magnetic disks, optical rotating recording media like optical disks and magneto-optical disks suffer from more defects. When a defect arises in the address information, it is no longer possible to access the data recording portion. Thus, the address information is written in the header two times or more to improve the reliability of the address information. Furthermore, an error detecting code is normally added to the address information.
Recently, under circumstances of technological advances such as the achievement of practical blue lasers and improvement of the recording density of magneto-optical disks, super compact, high density, large capacity magneto-optical disks having a diameter of 35 mm to 65 mm and a storage capacity of 2 GB to 4 GB such as described in Japanese Patent Application No. 11-176029 entitled xe2x80x9cOptical Medium and Disk Cartridgexe2x80x9d filed on Jun. 22, 1999 by the present applicant have been demanded.
If writing address information two or more times in such a super compact magneto-optical disk, the available data writing region decreases by the amount of writing of that redundant address information. Therefore, if the number of times of writing the redundant address information is decreased and the thus obtained region is used for the data writing region, the available data writing region increases.
However, defects also occur in such super compact magneto-optical disks, so if merely decreasing the number of times address information is redundantly written, a problem arises in reliability that data becomes unable to be read due to an unknown address when a defect occurs in the address information.
Such a problem is of course not limited to the above super compact magneto-optical disks and is also a problem to be dealt with for existing optical and magnetic disks.
A first object of the present invention is to provide an address information recording method capable of reducing a recording region of address information without reducing the reliability and an optical recording apparatus to which the method is applied.
A second object of the present invention is to provide an optical rotating recording medium recorded with address information by such an address information recording method.
A third object of the present invention is to provide an address information recovery method for effectively recovering address information recorded on such an optical recording media and an optical reproducing apparatus wherein the method is applied.
A fourth object of the present invention is to provide an optical recording/reproducing apparatus using said optical rotating recording media.
According to a first aspect of the present invention, there is provided an optical rotating recording medium wherein an address of the position and an error correction code generated for the address are recorded in an address information recording region inside headers of a land and/or groove.
Although there is just one address, since an error correction code having high correcting ability such as an error correction code of a Reed-Solomon system is added, it is possible to decode even if there is a defect. The bit length of the error correction code is shorter than the bit length of the address, so the amount of recording of an address and an error correction code in an optical rotating recording media decreases. As a result, the data recording region becomes larger.
According to a second aspect of the present invention, there is provided a method of recording address information for writing an address corresponding to an address information recording region of a land and/or groove of an optical rotating recording medium, including the steps of generating an error correction code for a corresponding address and recording the one address and a generated error correction code in said address information recording region.
According to a third aspect of the present invention, there is provided an optical recording apparatus comprising an address information generation means for generating an error correction code for each address of a land and/or groove of an optical rotating recording medium and combining one of the addresses and a generated error correction code and a recording means for recording address information generated by said address information generation means in an address information recording region of a land and/or groove on said optical rotating recording medium.
According to a fourth aspect of the present invention, there is provided a method of recovering address information, including the steps of reading one address and a corresponding error correction code recorded in the address information recording region of an optical rotating recording medium recorded with that one address and the error correction code generated for the address information in the address information recording region in a header of the land and/or groove; correcting the read address by the error correction code when there is error in the one read; and treating the correctly corrected address as a normal address and, when not correctly corrected, estimating and outputting a present address from at least one previous correct address in view of the continuity of addresses.
According to a fifth aspect of the present invention, there is provided an optical reproducing apparatus, comprising an optical detection means for reading one address and a corresponding error correction code recorded in the address information recording region of an optical rotating recording medium recorded with that one address and the error correction code generated for the address information in the address information recording region in a header of the land and/or groove and an address information recovery means for correcting any error in the one address detected by said optical detection means by said detected error correction code and using the correctly corrected address as a normal address and for estimating and outputting a present address from at least one previous correct address from the continuity of addresses when not correctly corrected.
Furthermore, according to a sixth aspect of the present invention, there is provided an optical recording/reproducing apparatus, comprising an address information generation means for generating an error correction code for each address of a land and/or groove on an optical rotating recording medium; a recording means for recording one address and a generated error correction code in an address information recording region of a land and/or groove on said optical rotating recording medium; an optical detection means for reading one address and a corresponding error correction code recorded in the address information recording region of an optical rotating recording medium recorded with that one address and the error correction code generated for the address information in the address information recording region in a header of the land and/or groove; an address information recovery means for correcting any error in the one address detected by said optical detection means by said detected error correction code and using the correctly corrected address as a normal address and for estimating and outputting a present address from at least one previous correct address from the continuity of addresses when not correctly corrected.
The optical rotating recording medium, address information recording method, optical recording apparatus, address information recovery method, an optical reproducing apparatus, and an optical recording/reproducing apparatus preferably use an error correction code of the Reed-Solomon system suitable to an optical rotating recording medium as said error correction code.
Preferably, said optical rotating recording medium has a diameter of 38 to 65 mm and a length of one address information recording region of 10 to 100 xcexcm.
For example, said address is 20 to 48 bits and said error correction code is 10 to 20 bits.
Preferably, said error correction code of the Reed-Solomon system is an error correction code generated for every four bits using symbols consisting of four bits. When performing the error correction code processing for every four bits, the distance between codes becomes longer compared with error correction processing for every eight bits and the correction capability declines.
The address information recovery means uses the address read one time previously and recovered without error as said at least one previous correct address.